Prophylactic use1 of drugs means prevention of certain diseases. Disinfectants, chemotherapeutic drugs and other are used for this purpose.
Etiotropic2 (causal3) therapy is aimed to eliminate the cause of the disease (thus, antibiotics affect bacteria, antimalarial drugs - malaria plasmodia).
The main task of symptomatic therapy is the elimination of unwanted symptoms (for example, pain), and thus significant influence on the basic pathologic process. Therefore, in many cases symptomatic therapy plays the role of the treatment of pathogenesis of the disease4.
Replacement therapy is used to treat the deficiency of natural biogenic substances. In the failure of endocrine glands (in diabetes mellitus, myxedema) appropriate hormones are administered. Duration of such therapy is measured in months and years.